The invention concerns a method and a system for measuring and processing driving-dynamic parameters of a vehicle. In particular, the invention concerns a method and a system for identifying a tyre of a vehicle by using the tyre pressures of the tyres to be identified.
Known systems for monitoring tyre pressures of different tyres of a vehicle comprise pressure sensor elements which are normally mounted on the rims and are surrounded by the corresponding tyres, or are mounted on the insides of the tyres, or are integrated into the tyres or the valve. The pressure sensor elements are respectively connected to a transmitter by which both the signals/data indicating the measured tyre pressures and an identification (ID information) which is characteristic of the corresponding pressure sensor elements are transmitted to a receiver. The receiver evaluates both the signals/data indicating the tyre pressures and the characteristic identifications.
Since the receiver does not obtain or receive any information in respect of which characteristic identification and which tyre pressure signals belong to which tyre, it is necessary to calibrate the tyre pressure monitoring system in such a way that the receiver can assign the information obtained from the transmitters to the corresponding pressure sensor elements.
Only on the basis of these assignments can the receiver and/or a control/monitoring unit connected to it provide information on which tyre pressure is present in which tyre and assign any drop in pressure to the corresponding tyre. Even in the event of a failure or malfunction of a pressure sensor element, the defective pressure sensor element can be identified in this way.
This calibration operation (which is also termed the learn mode) must be performed both when the wheel or tyre is first fitted on a factory-new vehicle and upon each subsequent wheel, tyre or valve change, since it cannot be ensured that, following changing, the wheels or the tyres are mounted according to the previous assignment.
The calibration operation is normally performed with the use of transponders which are integrated into corresponding sensor circuits of the sensor elements. Each of the transponders is individually activated, in a defined sequence, to transmit data, so that the characteristic identifications and the transmitted pressure information can be unambiguously assigned to the corresponding pressure sensor elements. In the case of a passenger car with four wheels and one spare wheel each having one tyre, the sequence for activating the individual transponders of the tyres can be defined as follows:
left front tyrexe2x80x94right front tyrexe2x80x94left rear tyrexe2x80x94right rear tyrexe2x80x94spare wheel tyre.
This procedure for identifying individual tyres of a vehicle and for assigning to the corresponding tyres sensor information which is measured at the corresponding tyres and transmitted to a receiver has various disadvantages. The recalibration of such tyre pressure monitoring systems is time-consuming and requires additional facilities for activating the transponders assigned to the individual pressure sensor elements. These facilities for activating the transponders are generally only available to the various specialist vehicle firms. For this reason, in order to ensure faultless functioning of the tyre pressure monitoring system, a tyre change should not be performed without recourse to a specialist vehicle firm, i.e., a tyre change performed by the driver/owner themselves. If, nevertheless, a tyre change is performed without recourse to a specialist vehicle firm, i.e., if it is performed privately or if no calibration operation is performed when a tyre is changed, faultless functioning of the tyre pressure monitoring system is no longer assured. Moreover, malfunctions of the tyre pressure monitoring system can occur if, for example, the tyre pressure monitoring system can no longer be provided with the current assignment. This can occur, for example, if a memory in which the current assignment is stored is inadvertently/accidentally erased. In such cases, it is necessary to repeat the calibration operation with such tyre pressure monitoring systems, this normally requiring the vehicle to be brought into an appropriate specialist firm. In any case, the operation of the vehicle has to be interrupted, since the recalibration of the tyre pressure monitoring system cannot be performed independently/automatically by the latter and/or during the driving operation of the vehicle.
A method is known from DE 196 32 150 A1 for monitoring the air pressure in the tyres of motor vehicle wheels, in which long-wave units, which are respectively assigned to a tyre and transmit long-wave signals, are used for identifying the individual tyres. The long-wave signals are respectively received by a long-wave receiving unit of a wheel module assigned to a tyre, and are processed to generate a long-wave identification signal. Each of the wheel modules transmits the corresponding long-wave identification signal together with a data signal, which indicates the respective tyre pressure, to a receiving unit located on the vehicle. The positions of the motor vehicle wheels can be unambiguously assigned to the data signals transmitted by the wheel modules on the basis of the long-wave identification signals contained in the data signals. A disadvantage in this case is that, in addition to the components for measuring the tyre pressures, it is necessary for components to be located on the tyres or wheels and on the vehicle for the purpose of transmitting the long-wave signals, as well as generating the long-wave identification signals, embedding them in the data signals and extracting them from the data signals again following their transmission.
Proceeding from this, the invention is intended to provide a method and a system which render possible, without time-consuming and cost-intensive recalibration, unambiguous identification of tyres of a vehicle and unambiguous identification of sensor signals, relating to the corresponding tyres, measured at the tyres. Furthermore, the invention is intended to provide a solution which avoids the need to use additional devices (e.g., transponders, long-wave transmission units) for the calibration operation. In addition, malfunctions of a tyre pressure monitoring system are to be reduced, and corrected in a simple manner.
To achieve these objects, the invention provides a method according to claim 1 and a system according to claim 12.
In the case of the method, according to the invention, for identifying a tyre of a vehicle, a tyre pressure of a vehicle tyre is measured for at least two different driving-dynamic states of the vehicle and the measured tyre pressures are compared for the purpose of determining a tyre pressure variation on the basis of this comparison. The determined tyre pressure variation is analysed using driving state parameters which are determined by the at least two different driving-dynamic states. The vehicle tyre at which the tyre pressures were measured is identified on the basis of the analysis of the tyre pressure variation.
This procedure is based on the fact that the dynamic tyre circumferences vary in dependence on the respective prevailing driving-dynamic state of the vehicle. This variation of the dynamic tyre circumferences results in a tyre pressure variation in the corresponding tyre. If the tyre pressures of a tyre, or its variations, are determined and if information is available which permits description/definition of the driving-dynamic state of the vehicle causing the tyre pressure variations, the vehicle tyre at which the tyre pressures were measured can be unambiguously identified.
In addition, the measurement and comparison of the tyre pressures can be performed for at least one tyre of at least two different wheels of the vehicle. In this way, several, preferably all, tyres of the vehicle can be identified. Furthermore, it is possible thus to identify several tyres assigned to one wheel of the vehicle. This is the case, for example, in the case of lorries with twin tyres.
In addition, it is possible to measure and compare with one another the tyre pressure of all tyres at which tyre pressures have been measured. Analysis of the tyre pressures can then be performed using information which comprises the previously recorded tyre pressures or tyre pressure variations, reference tables and information used for the application of neural networks or chaos-theory methods. In this way, the identification of the individual tyres of the vehicle can be performed more rapidly and with greater exactness, since not only driving state parameters, but also information resulting from the comparison of the tyre pressures of all wheels is used for analysing the at least one pressure variation. This additional information permits a more accurate description of the driving-dynamic state of the vehicle in which the tyre pressures are determined. Moreover, there is a reduction of the number of different driving-dynamic states of the vehicle in which tyre pressures of the tyres have to be measured in order for individual tyres of the vehicle to be unambiguously identified.
In order to simplify the method according to the invention, the measurement of the tyre pressures can include at least one measurement of the tyre pressures for a predetermined driving-dynamic state of the vehicle. In this case, a tyre pressure is preferably measured, for one, several or all tyres of the vehicle, in a predetermined driving-dynamic state of the vehicle. Such a predetermined/predefined driving-dynamic state of the vehicle can be, for example, straight forward travel of the vehicle at a constant speed or predefined constant acceleration. Furthermore, it is also possible in this case to measure tyre pressures of tyres when the vehicle is operated but not in motion (e.g. when the vehicle is in a parked position and the ignition is switched on or the engine is started).
In addition, the method can also include a measurement of driving state parameters that are determined by driving-dynamic states of the vehicle. In this way, it is no longer necessary for the required driving state parameters to be provided by other components of the vehicle which perform corresponding methods for measuring driving state parameters. The measurement of driving state parameters can also be thus optimised, in that the measurement of the driving state parameters is specially adapted to the identification of tyres.
Driving-dynamic states of the vehicle are preferably determined from the corresponding driving state parameters. This enables information that comprehensively represents the driving-dynamic states of the vehicle to be used in analysis of the tyre pressure variations, without the need to use individual driving state parameters. To determine the driving-dynamic states of the vehicle from the corresponding driving state parameters, it is possible to use known algorithms, reference tables, calculation methods used on neural networks or a fuzzy logic, and data/information, provided in the use of other methods, for determining driving-dynamic states of the vehicle, which are performed by vehicle components specially designed for this purpose.
Furthermore, data can be stored which is used for identifying individual tyres or all tyres of the vehicle. This data for identifying tyres can be used during the operation of the vehicle, so that it is not necessary to repeat performance of the method according to the invention for identifying tyres.
Since it cannot be assured that no tyre change has been performed between a termination and a resumption of operation of the vehicle, it is preferable that the method be performed upon each restarting of the vehicle.
In order that unambiguous identification of tyres is also assured during driving operation of the vehicle in every situation (e.g. in the case of a malfunction of electrical/electronic vehicle components), it is preferable that the method according to the invention be performed at predetermined times or at predetermined intervals of time, i.e., repeatedly, during a driving operation of the vehicle.
An object of the invention is also achieved with a system for identifying a tyre of a vehicle. For this, the system includes a device located at a tyre of a vehicle for the purpose of measuring tyre pressures, and a transmitting device, connected to the device for measuring the tyre pressures, for the purpose of transmitting tyre pressure signals. These tyre pressure signals of the transmitting device are received by a receiver device and transmitted to a processor device which is connected to the receiver device for the purpose of processing the tyre pressure signals. The system according to the invention also includes at least one device for measuring driving state parameters which characterize the driving-dynamic states of the vehicle. The at least one device for measuring the driving state parameters is connected to the processor device for the purpose of transmitting these parameters. The processor device is designed, according to the invention, in such a way that it determines tyre pressure variations for the tyres from the tyre pressure signals and evaluates them, using the driving state parameters, for the purpose of providing data/information which serves to identify the tyre at which the device for measuring the tyre pressure is located.
A device for measuring the corresponding tyre pressures is preferably respectively located at each of at least two tyres which are each respectively assigned to a wheel of the vehicle, each of the devices for measuring the tyre pressures being connected to a corresponding transmitter, and the receiver device being set up to receive pressure signals of all transmitting devices.
The processor device should also be designed so that it determines tyre pressure variations for each tyre at which one of the devices for measuring tyre pressures is located, and evaluates them using the driving state parameters. In this way, it is possible to assign tyre pressure variations to the corresponding tyres, so that each tyre is identified.
The device for measuring tyre pressure variations preferably comprises a pressure sensor.
The at least one device for measuring the driving state parameters should also comprise at least one sensor for measuring driving-dynamic state quantities.
The device for measuring tyre pressures or the transmitting device can also have a characteristic identification which is transmitted to the receiver device by the transmitting device before, after or isochronously with the tyre pressure signals.
In order that the system according to the invention can be used in vehicles with a different number of tyres and/or a different number of devices for measuring tyre pressure variations and corresponding transmitting devices, the receiver device comprises receiving units respectively assigned to a transmitting device for the purpose of receiving signals from the latter. This permits a modular construction of the system according to the invention, which can be adapted to the particular application instance (e.g. vehicle type).
Preferred embodiments of the invention are described in the following, with reference to the appended FIG. 1.